I've been looking at Rider #496 and I've got a suspicion that (s)he is headed for Phoenix. From there (s)he will go North to Salt Lake City and West to Carson City. What (s)he does after that will depend on whether (s)he already has three of the four corners.
Yes - (s)he goes to San Ysidro for the fourth corner.
No - (s)he goes to Sacramento.
Then on to Ontario. Of course, this all is only workable if (s)he got Colorado on leg #1.
If (s)he has to still get Colorado, then (s)he would have to skip both of the above after Carson City or Carson City & Sacramento so (s)he could get San Ysidro. It will be interesting to see where Rider #496 goes.
That figures. As soon as I posted the above Spotwalla updates, and now shows Rider #496 turning North toward Santa Fe. Never mind.